What Causes Shortness Of Breath While Suffering From Acute Myocardial Infarction?

I had an acute MI on September 23rd. Since then, my shortness of breath has gotten progressively worse. The week after my MI, I was taking 10-15 walks with no problems...only got slightly winded. Now I get winded walking across the room, in conversation and singing (I m in the choir). I have had a nuclear stress test, CT s with and without contrast, chest x-rays and EKGs...all within normal limits. The only thing I can see that is slightly off is that my left ventricular ejection fraction is sitting at 72-75%. I am 53 years old. I have low blood pressure (110/60), I have NEVER smoked. I am not diabetic or prediabetic. My total cholesterol is 149 and my HDL is 38. I am overweight (150 pounds at 4 10 ) and I have really crappy genes. Heart disease in the MEN on both sides of my family. As far as I know, I am the first woman. Oh, and I did not have this problem AT ALL before my STEMI. Any input will be appreciated.